/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.library.dprofile;

import org.apache.iotdb.commons.udf.utils.UDFDataTypeTransformer;
import org.apache.iotdb.library.util.NoNumberException;
import org.apache.iotdb.tsfile.file.metadata.enums.TSDataType;
import org.apache.iotdb.udf.api.UDTF;
import org.apache.iotdb.udf.api.access.Row;
import org.apache.iotdb.udf.api.collector.PointCollector;
import org.apache.iotdb.udf.api.customizer.config.UDTFConfigurations;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameterValidator;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameters;
import org.apache.iotdb.udf.api.customizer.strategy.RowByRowAccessStrategy;
import org.apache.iotdb.udf.api.type.Type;

/**
 * This function is used to calculate the spread of time series, that is, the maximum value minus
 * the minimum value.
 */
public class UDAFSpread implements UDTF {

    int intMin = Integer.MAX_VALUE, intMax = Integer.MIN_VALUE;
    long longMin = Long.MAX_VALUE, longMax = Long.MIN_VALUE;
    float floatMin = Float.MAX_VALUE, floatMax = -Float.MAX_VALUE;
    double doubleMin = Double.MAX_VALUE, doubleMax = -Double.MAX_VALUE;
    TSDataType dataType;

    @Override
    public void validate(UDFParameterValidator validator) throws Exception {
        validator
                .validateInputSeriesNumber(1)
                .validateInputSeriesDataType(0, Type.INT32, Type.INT64, Type.FLOAT, Type.DOUBLE);
    }

    @Override
    public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations)
            throws Exception {
        dataType = UDFDataTypeTransformer.transformToTsDataType(parameters.getDataType(0));
        configurations
                .setAccessStrategy(new RowByRowAccessStrategy())
                .setOutputDataType(UDFDataTypeTransformer.transformToUDFDataType(dataType));
    }

    @Override
    public void transform(Row row, PointCollector pc) throws Exception {
        switch (dataType) {
            case INT32:
                transformInt(row, pc);
                break;
            case INT64:
                transformLong(row, pc);
                break;
            case FLOAT:
                transformFloat(row, pc);
                break;
            case DOUBLE:
                transformDouble(row, pc);
                break;
        }
    }

    @Override
    public void terminate(PointCollector pc) throws Exception {
        switch (dataType) {
            case INT32:
                pc.putInt(0, intMax - intMin);
                break;
            case INT64:
                pc.putLong(0, longMax - longMin);
                break;
            case FLOAT:
                pc.putFloat(0, floatMax - floatMin);
                break;
            case DOUBLE:
                pc.putDouble(0, doubleMax - doubleMin);
                break;
            default:
                throw new NoNumberException();
        }
    }

    private void transformInt(Row row, PointCollector pc) throws Exception {
        int v = row.getInt(0);
        intMin = Math.min(intMin, v);
        intMax = Math.max(intMax, v);
    }

    private void transformLong(Row row, PointCollector pc) throws Exception {
        long v = row.getLong(0);
        longMin = Math.min(longMin, v);
        longMax = Math.max(longMax, v);
    }

    private void transformFloat(Row row, PointCollector pc) throws Exception {
        float v = row.getFloat(0);
        if (Float.isFinite(v)) {
            floatMin = Math.min(floatMin, v);
            floatMax = Math.max(floatMax, v);
        }
    }

    private void transformDouble(Row row, PointCollector pc) throws Exception {
        double v = row.getDouble(0);
        if (Double.isFinite(v)) {
            doubleMin = doubleMin < v ? doubleMin : v;
            doubleMax = doubleMax > v ? doubleMax : v;
        }
    }
}
